FINRA will examine fifteen (15) of the systems initially. ATS included “crossing networks, such as ITG’s Posit or Goldman Sachs’ Sigma X, which match trades without first routing orders to a public exchange; block-trading venues such as Liquidnet or the BIDS ATS; and electronic communications networks, which display public quotes, such as LavaFlow, operated by Citigroup, or Light Pool, operated by Credit Suisse.”

One area FINRA will focus on are called dark pools. Dark pools are systems that allow anonymous trading off public exchanges. The largest of these is Crossfinder, which is operated by Credit Suisse. Dark pools accounted for 13.3% of all equities trading in 2012. In January 2012, 2.4 billion shares of stock were traded off exchanges, accounting for 36.7% of all trading for that month.

John Malitzis, executive vice president of market regulation at FINRA, stated “we are looking at the use of indications of interest, whether the firm trades as principal or riskless principal within the ATS, and whether and how this is disclosed to ATS subscribers. We are also looking at the method by which the ATS generates compensation, how customer errors are handled, and whether and how affiliates of the ATS interact with order flow.”